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Förslaget inkom 2006-01-18

Induction of pathogenesis-related proteins in barley during infestation with the aphid Rhopalosiphum padi

Plants react with a variety of defenses upon attack by herbivores and pathogens. In our group we are studying how cereals defend themselves against aphids, using barley, Hordeum vulgare and the bird-cherry oat aphid (Rhopalosiphum padi) as an example. Not all barley varieties are equally susceptible to aphids. There are resistant lines on which R. padi will not grow as well as on a susceptible variety. The basis for this resistance is still not well understood. Sucking insects (like aphids) cause different reactions in the plant than chewing herbivores. An increased knowledge about the plants defense reactions against aphid attack will improve our possibilities to protect plants.
Like in defense reactions against fungal or bacterial pathogens, glucanases and chitinases, two groups of PR proteins, are induced upon aphid infestation. From previous studies we know that this induction is stronger in resistant than in susceptible varieties. The induction was studied on protein level by western blot analysis. Both proteins are encoded by mulitgene families with several members in barley. It is not known which of these genes is coding for the protein that is induced by aphids attack. Using gene-specific primers it is possible to distinguish between these gene family members by reverse transcription (RT) PCR. In addition, two-dimensional protein gel studies showed that another PR protein (PR17) is induced by aphids. This PR protein has so far only been found to be induced in barley by a pathogenic fungus.
The aim of this project is to: (i) identify which chitinase gene is the one induced by aphids in barley using gene-specific primers and RTPCR and (ii) confirm the results obtained for PR17 by 2D-protein gels with western blot analysis of time course experiments using a specific antiserum and by northern blot or RTPCR analysis.

The project involves the extraction of proteins and RNA from barley with and without aphid infestation. The expression of PR proteins will be examined on protein level by using antisera and at RNA level with northern blots and RTPCR. Both a resistant and a susceptible barley variety will be included in the experiments and their reactions to aphid attack compared at various time points of the infestation.

Suitable background for this project would be an education in biology, biotechnology or molecular cell biology with training in molecular techniques. Some knowledge of plant biology would be an advantage.

The department of chemistry, biology, geography and environmental sciences at Södertörn University College has about 150 members, of which about 50 post-graduate students. The department has an active research focused on the life sciences, and is located in new buildings with modern equipment suitable for molecular research.


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